The accuracy of measurement equipment may drift gradually over time due to, for example, aging of components, temperature, humidity, environmental exposure, and abuse. To ensure measurement accuracy, periodic calibration of the equipment can be performed. By comparing measurements performed with the equipment to a known reference, correction factors can be determined and stored for use in conjunction with future measurements with the equipment. A reference source may be, for example, additional equipment configured to output a certain condition, (e.g., voltage, current, resistance, etc.) and provide the parameters associated with that condition at a certain resolution (e.g., milliamps, microamps, etc.) that can be used for performing calibration of the measurement instrument.
Typically, if a measurement instrument can perform measurements of a given resolution, the measurement parameters of a reference source that is used for calibration should be known at a higher resolution than that of the measurement instrument, usually at least an order or two higher to account for noise in the measurement process. If, however, the measurement instrument has a high resolution, the process for devising the measurement parameters of a reference source having an even higher resolution can be quite expensive.